First time Leonard & Sheldon met Penny

At the top of the stairs, they spot Penny, who is moving into the apartment across the hall from them. Leonard and Sheldon agree that she is an improvement over their old neighbor, Louie/Louise, who, according to Sheldon, was a 200-pound transvestite with a skin condition. After Penny spots them, they exchange two rounds of "hi". Penny learns that they are her neighbors from across the hall. She offers to have coffee with them later.